The present invention relates to vehicle anti-theft security (VATS) systems, and more particularly, to a key assembly for use in an automobile steering column ignition and lock unit.
The development of numerous different electronic VATS systems for an automobile has taken place over the years. One such system incorporates the use of a resistor pellet in an ignition key. The pellet provides for a resistor of known resistance so that upon insertion and rotation of the key in an automobile's ignition cylinder unit an electrical current is applied to and through the resistor. A decoding circuit performs a resistance comparison between the pellet in the key and a known resistance "window" in the circuit. If the resistance is within the window, the automobile may be started. If the resistance does not match, the automobile will not start.
The current art provides for attachment of the pellet by sonic welding techniques. A problem with this type of attachment is that flashing, caused by sonic welding, from the plastic material comprising the outer portion of the pellet, could cover the exposed metal surface contacts of the resistor imbedded in the plastic material. If the contacts become covered, they are not capable of completing the decoding circuit and the automobile will not start even if the operator has the correct key. Further, the sonic weld could be weakened as a result of poor alignment of parts or contamination of surfaces by oil and humidity, for example.
Another potential problem is a bad solder attachment. There could be a short solder joint, creating a weakness in the attachment of the resistor to the metal contacts. A further problem is the possibility of heat from the sonic welding causing the solder which joins the exposed contacts within the pellet to break, resulting in an inoperative key.